high risk

The long-term ramifications of head injuries and rotational motion     

By Joe Brandel

Common accidents in construction
    The primary causes of both fatal and non-fatal traumatic brain injuries in construction are contact with objects and equipment, and slips, trips and falls.² These accidents can be especially dangerous when someone’s head makes impact, with either the ground or a falling object, at an angle. This is often the case, as most impacts are likely to occur at an oblique angle, exposing the head to rotational motion.

What is rotational motion?
    A combination of rotational forces (angular acceleration) and rotational energy (angular velocity), rotational motion is a result of angled impacts to the head. When rotational motion is transferred to the brain, the brain cells can start to move relative to each other and shearing can occur. This may damage the axons, or the cable transmitters of neurons, inside the brain.
    During most impacts, both linear motion, primarily caused by straight impacts, and rotational motion occur together. Notably, the two different types of motions often cause different types of injuries. For example, focal injuries such as skull fractures and contusions are primarily caused bylinear motion, while diffuse injuries such as diffuse axonal injury and subdural hematoma are more often caused by rotational motion.³⁴
    Experiments have shown that the brain is more sensitive to rotational motion than linear motion in regard to concussions.⁵ When rotational motion is involved, even impacts that were considered light have the potential to cause concussions, due to the brain’s sensitivity.

Prioritize helmet safety
    To try and increase protection against potential traumatic brain injuries, those at risk of head injuries in any industry should wear a helmet. Make sure that it fits securely and is comfortable. The best helmet is the one that you’ll want to wear. Then, you may also consider a helmet that has a system in place intended to help mitigate rotational motion.
    Generally, most helmets available today are designed and tested to protect wearers from linear motion, protecting against linear impacts to the crown of the helmet, which they do quite well. However, more attention should be paid to addressing rotational motion, which can be a big threat to workers’ risk of traumatic brain injuries.
    Despite the fact that off-center impacts to the head are considered to be common among accident scenarios and known to potentially cause brain injuries, regulatory standards today don’t take this into account. It’s important to note that helmets are not certified based on their ability to mitigate against the impacts of rotational motion from off-center or angled impacts. Other standards in the moto and sports industries are beginning to test angled impacts, which demonstrates the growing awareness of the harm that rotational motion may cause.

What next?
    Those in the construction industry should take note as many jobsite accidents, whether a trip or a falling object, are not caused by a purely linear impact to the head. In real life scenarios, most falls occur at angle, which can create rotational motion.
    Increasing awareness of the harmful effects of rotational motion, and how it can be caused, is one of the first steps towards workers’ safety. Additionally, the importance of helmet safety and safe PPE practices cannot be overstated. A survey conducted by J.J. Keller Safegear, a PPE provider, reported 50% of the respondents did not wear PPE because they didn’t think it was necessary.⁶
    Alerting the industry to rotational motion and its risks is just part of the journey. Workers must practice safe helmet usage and should prioritize using helmets that are designed to also address rotational motion.